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Sep 20, 2013
09/13

by
K. A. Bronnikov

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Examples of nonsingular cosmological models are presented on the basis of exact solutions to multidimensional gravity equations. These examples involve pure imaginary scalar fields, or, in other terms, ``phantom'' fields with an unusual sign of the kinetic term in the Lagrangian. We show that, with such fields, hyperbolic nonsingular models with a cosmological bounce (unlike spherical and spatially flat models) emerge without special relations among the integration constants, i.e., without fine...

Source: http://arxiv.org/abs/gr-qc/0410119v1

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Sep 18, 2013
09/13

by
K. A. Bronnikov

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Multidimensional cosmological, static spherically symmetric and Euclidean configurations are described in a unified way for gravity interacting with several dilatonic fields and antisymmetric forms, associated with electric and magnetic p-branes. Exact solutions are obtained when certain vectors, built from the input parameters of the model, are either orthogonal in the minisuperspace, or form mutually orthogonal subsystems. Some properties of black-hole solutions are indicated, in particular,...

Source: http://arxiv.org/abs/hep-th/9710207v3

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Sep 23, 2013
09/13

by
K. A. Bronnikov

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Multidimensional gravity interacting with intersecting electric and magnetic $p$-branes is considered for fields depending on a single variable. Some general features of the system behaviour are revealed without solving the field equations. Thus, essential asymptotic properties of isotropic cosmologies are indicated for different signs of spatial curvature; a no-hair-type theorem and a single-time theorem for black holes are proved (the latter makes sense in models with multiple time...

Source: http://arxiv.org/abs/gr-qc/9806102v1

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Sep 22, 2013
09/13

by
K. A. Bronnikov

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Exact static, spherically symmetric solutions to the Einstein-Abelian gauge-dilaton equations, in $D$-dimensional gravity with a chain of $n$ Ricci-flat internal spaces are considered, with the gauge field potential having three nonzero components: the temporal, Coulomb-like one, the one pointing to one of the extra dimensions, and the one responsible for a radial magnetic field. For dilaton coupling implied by string theory an $(n+5)$-parametric family of exact solutions is obtained, while for...

Source: http://arxiv.org/abs/gr-qc/9505020v3

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Sep 22, 2013
09/13

by
K. A. Bronnikov; S. Grinyok

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Static, spherically symmetric, traversable wormholes, induced by massless, nonminimally coupled scalar fields in general relativity, are shown to be unstable under spherically symmetric perturbations. The instability is related to blowing-up of the effective gravitational constant on a certain sphere.

Source: http://arxiv.org/abs/gr-qc/0201083v2

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Sep 19, 2013
09/13

by
K. A. Bronnikov; E. Elizalde

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The properties of static, spherically symmetric configurations are considered in the framework of two models of nonlocally corrected gravity, suggested in S. Deser and R. Woodard., Phys. Rev. Lett. 663, 111301 (2007), and S. Capozziello et al., Phys. Lett. B 671, 193 (2009). For the first case, where the Lagrangian of nonlocal origin represents a scalar-tensor theory with two massless scalars, an explicit condition is found under which both scalars are canonical (non-phantom). If this condition...

Source: http://arxiv.org/abs/0910.3929v3

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Sep 22, 2013
09/13

by
K. A. Bronnikov; S. Grinyok

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Static, spherically symmetric, traversable wormhole solutions with electric or magnetic charges are shown to exist in general relativity in the presence of scalar fields nonminimally coupled to gravity. These wormholes, however, turn out to be unstable under spherically symmetric perturbations. The instability is related to blowing-up of the effective gravitational constant on a certain sphere.

Source: http://arxiv.org/abs/gr-qc/0205131v1

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Sep 18, 2013
09/13

by
K. A. Bronnikov; I. G. Dymnikova

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We present the class of regular homogeneous T-models with vacuum dark fluid, associated with a variable cosmological term. The vacuum fluid is defined by the symmetry of its stress-energy tensor, i.e., its invariance under Lorentz boosts in a distinguished spatial direction (p_j=-\rho), which makes this fluid essentially anisotropic and allows its density to evolve. Typical features of homogeneous regular T-models are: the existence of a Killing horizon; beginning of the cosmological evolution...

Source: http://arxiv.org/abs/0705.2368v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; O. B. Zaslavskii

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We study equilibrium conditions between a static, spherically symmetric black hole and classical matter in terms of the radial pressure to density ratio p_r/\rho = w(u), where u is the radial coordinate. It is shown that such an equilibrium is possible in two cases: (i) the well-known case w\to -1 as $u\to u_h (the horizon), i.e., "vacuum" matter, for which \rho(u_h) can be nonzero; (ii) w \to -1/(1+2k) and \rho \sim (u-u_h)^k as u\to u_h, where k>0 is a positive integer (w=-1/3 in...

Source: http://arxiv.org/abs/0801.0889v2

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Sep 22, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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Vacuum cosmological models are considered in the context of a multidimensional theory of gravity with integrable Weyl geometry. A family of exact solutions with a chain of internal spaces is obtained. Models with one internal space are considered in more detail; nonsingular models are selected.

Source: http://arxiv.org/abs/gr-qc/9410038v1

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Sep 22, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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We review some results concerning the properties of static, spherically symmetric solutions of multidimensional theories of gravity: various scalar-tensor theories and a generalized string-motivated model with multiple scalar fields and fields of antisymmetric forms associated with p-branes. A Kaluza-Klein type framework is used: there is no dependence on internal coordinates but multiple internal factor spaces are admitted. We discuss the causal structure and the existence of black holes,...

Source: http://arxiv.org/abs/gr-qc/0310112v1

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Sep 21, 2013
09/13

by
K. A. Bronnikov; O. B. Zaslavskii

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It is shown that only particular kinds of matter (in terms of the "radial" pressure to density ratio $w$) can coexist with Killing horizons in black-hole or cosmological space-times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter ($w=-1$, i.e., the cosmological constant or some its generalization) and matter with certain values of $w$ between 0 and -1, in particular, a gas of disordered cosmic strings ($w=-1/3$). If the...

Source: http://arxiv.org/abs/0905.4425v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; S. G. Rubin

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We show that the problem of stabilization of extra dimensions in Kaluza-Klein type cosmology may be solved in a theory of gravity involving high-order curvature invariants. The method suggested (employing a slow-change approximation) can work with rather a general form of the gravitational action. As examples, we consider pure gravity with Lagrangians quadratic and cubic in the scalar curvature and some more complex ones in a simple Kaluza-Klein framework. After a transition to the 4D Einstein...

Source: http://arxiv.org/abs/gr-qc/0510107v2

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Sep 22, 2013
09/13

by
K. A. Bronnikov; B. E. Meierovich

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We review some recent results concerning the properties of a spherically symmetric global monopole in $(D=d+2)$-dimensional general relativity. Some common features of monopole solutions are found independently of the choice of the symmetry-breaking potential. Thus, the solutions show six types of qualitative behavior and can contain at most one simple horizon. For the standard Mexican hat potential, we analytically find the $D$-dependent range of $\gamma$ (the gravitational field strength...

Source: http://arxiv.org/abs/gr-qc/0310126v1

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Sep 21, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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The validity conditions for the extended Birkhoff theorem in multidimensional gravity with $n$ internal spaces are formulated, with no restriction on space-time dimensionality and signature. Examples of matter sources and geometries for which the theorem is valid are given. Further generalization of the theorem is discussed.

Source: http://arxiv.org/abs/gr-qc/9403063v1

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Sep 17, 2013
09/13

by
K. A. Bronnikov; J. C. Fabris

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Exact cosmological solutions for effective actions in D dimensions inspired by the tree-level superstring action are studied. For a certain range of free parameters existing in the model, nonsingular bouncing solutions are found. Among them, of particular interest can be open hyperbolic models, in which, without any fine tuning, the internal scale factor and the dilaton field (connected with string coupling in string theories) tend to constant values at late times. A cosmological singularity is...

Source: http://arxiv.org/abs/hep-th/0207213v1

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Sep 22, 2013
09/13

by
K. A. Bronnikov; U. Kasper; M. Rainer

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We consider a D-dimensional self-gravitating spherically symmetric configuration of a generalized electro-magnetic n-form F and a dilatonic scalar field, admitting an interpretation in terms of intersecting p-branes. For theories with multiple times, selection rules are obtained, which obstruct the existence of p-branes in certain subspaces. General static solutions are obtained under a specific restriction on the model parameters, which corresponds to the known "intersection rules"....

Source: http://arxiv.org/abs/gr-qc/9708058v1

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Sep 21, 2013
09/13

by
K. A. Bronnikov; S. G. Rubin

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We show that a number of problems of modern cosmology may be addressed and solved in the framework of multidimensional gravity with high-order curvature invariants, without invoking other fields. As applications of this approach, we mention primordial inflation and particle production after it; description of the modern accelerated stage of the Universe with stable compact extra dimensions; construction of asymmetric thick brane-world models.

Source: http://arxiv.org/abs/0712.0888v2

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Sep 20, 2013
09/13

by
K. A. Bronnikov; M. S. Chernakova

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Many theories of gravity admit formulations in different, conformally related manifolds, known as the Jordan and Einstein conformal frames. Among them are various scalar-tensor theories of gravity and high-order theories with the Lagrangian $f(R)$ where $R$ is the scalar curvature and $f$ an arbitrary function. It may happen that a singularity in the Einstein frame corresponds to a regular surface S_trans in the Jordan frame, and the space-time is then continued beyond this surface. This...

Source: http://arxiv.org/abs/gr-qc/0601123v2

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Sep 18, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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In multidimensional gravity with an arbitrary number of internal Ricci-flat factor spaces, interacting with electric and magnetic $p$-branes, spherically symmetric configurations are considered. It is shown that all single-brane black-hole solutions are stable under spherically symmetric perturbations, whereas similar solutions possessing naked singularities turn out to be catastrophically unstable. The black hole stability conclusion is extended to some classes of configurations with...

Source: http://arxiv.org/abs/hep-th/0002200v1

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Jul 20, 2013
07/13

by
K. A. Bronnikov; O. B. Zaslavskii

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We study the conditions of a possible static equilibrium between spherically symmetric, electrically charged or neutral black holes and ambient matter. The following kinds of matter are considered: (1) neutral and charged matter with a linear equation of state p_r = w\rho (for neutral matter the results of our previous work are reproduced), (2) neutral and charged matter with p_r \sim \rho^m, m > 1, and (3) the possible presence of a "vacuum fluid" (the cosmological constant or,...

Source: http://arxiv.org/abs/1107.4701v3

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Sep 19, 2013
09/13

by
K. A. Bronnikov; B. E. Meierovich

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We consider (d_0+2)-dimensional configurations with global strings in the two extra dimensions and a flat metric in d_0 dimensions, endowed with a warp factor e^{2\gamma} depending on the distance l from the string center. All possible regular solutions to the field equations are classified by the behavior of the warp factor and the extra-dimensional circular radius r(l). Solutions with r\to \infty and r\to \const >0 as l\to \infty are interpreted in terms of thick brane world models....

Source: http://arxiv.org/abs/0708.3439v2

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Sep 24, 2013
09/13

by
K. A. Bronnikov; E. A. Tagirov

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Fock representations are constructed for a free scalar field in the closed and quasi-Euclidean isotropic cosmological models. Invariance of their cyclic vector (vacuum) under isometries and the correspondence principle single out a class of unitarily equivalent representations.

Source: http://arxiv.org/abs/gr-qc/0412138v1

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Sep 19, 2013
09/13

by
K. A. Bronnikov; B. E. Meierovich

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Multidimensional configurations with Minkowski external space-time and a spherical global monopole in extra dimensions are discussed in the context of the brane world concept. The monopole is formed with a hedgehog-like set of scalar fields \phi^i with a symmetry-breaking potential V depending on the magnitude \phi^2 = \phi^i \phi^i. All possible kinds of globally regular configurations are singled out without specifying the shape of V(\phi). These variants are governed by the maximum value...

Source: http://arxiv.org/abs/gr-qc/0507032v1

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Sep 18, 2013
09/13

by
K. A. Bronnikov; Sung-Won Kim

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The condition R=0, where R is the four-dimensional scalar curvature, is used for obtaining a large class (with an arbitrary function of r) of static, spherically symmetric Lorentzian wormhole metrics. The wormholes are globally regular and traversable, can have throats of arbitrary size and can be both symmetric and asymmetric. These metrics may be treated as possible wormhole solutions in a brane world since they satisfy the vacuum Einstein equations on the brane where effective stress-energy...

Source: http://arxiv.org/abs/gr-qc/0212112v1

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Jul 20, 2013
07/13

by
K. A. Bronnikov; S. A. Kononogov

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We briefly review the recent experimental results on possible variations of the fine structure constant $\alpha$ on the cosmological time scale and its position dependence. We outline the theoretical grounds for the assumption that $\alpha$ might be variable, mention some phenomenological models incorporating a variable $\alpha$ into the context of modern cosmology and discuss the significance of possible $\alpha$ variations for theoretical and practical metrology.

Source: http://arxiv.org/abs/gr-qc/0604002v3

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Sep 23, 2013
09/13

by
K. A. Bronnikov; O. B. Zaslavskii

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For arbitrary static space-times, it is shown that an equilibrium between a Killing horizon and matter is only possible for some discrete values of the parameter $w = p_1/\rho$, where $\rho$ is the density and $p_1$ is pressure in the direction normal to the horizon. In the generic situation of a simple (non-extremal) horizon and the slowest possible density decrease near the horizon, this corresponds to $w = -1/3$, the value known for a gas of disordered cosmic strings. An admixture of...

Source: http://arxiv.org/abs/0904.4904v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; J. C. Fabris

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For self-gravitating, static, spherically symmetric, minimally coupled scalar fields with arbitrary potentials and negative kinetic energy (favored by the cosmological observations), we give a classification of possible regular solutions to the field equations with flat, de Sitter and AdS asymptotic behavior. Among the 16 presented classes of regular rsolutions are traversable wormholes, Kantowski-Sachs (KS) cosmologies beginning and ending with de Sitter stages, and asymptotically flat black...

Source: http://arxiv.org/abs/gr-qc/0511109v1

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Sep 24, 2013
09/13

by
K. A. Bronnikov; E. V. Donskoy

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A black universe is a nonsingular black hole where, beyond the horizon, there is an expanding, asymptotically isotropic universe. Such models have been previously found as solutions of general relativity with a phantom scalar field as a source of gravity and, without phantoms, in a brane world of RS2 type. Here we construct examples of static, spherically symmetric black-universe solutions in general relativity with a minimally coupled scalar field \phi whose kinetic energy is negative in a...

Source: http://arxiv.org/abs/1110.6030v1

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Sep 22, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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Vacuum static, axially symmetric space-times in $D$-dimensional general relativity with a Ricci-flat internal space are discussed. It is shown, in particular, that some of the monopole-type solutions are free of curvature singularities and their source can be a disk membrane bounded by a ring with a string or branching type singularity. Another possibility is a wormhole configuration where a particle can penetrate to another spatial infinity by passing through a ring with a string or branching...

Source: http://arxiv.org/abs/gr-qc/9505021v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; S. V. Grinyok

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We study the stability of static, spherically symmetric, traversable wormholes existing due to conformal continuations in a class of scalar-tensor theories with zero scalar field potential (so that Fisher's well-known scalar-vacuum solution holds in the Einstein conformal frame). Specific examples of such wormholes are those with nonminimally (e.g., conformally) coupled scalar fields. All boundary conditions for scalar and metric perturbations are taken into account. All such wormholes are...

Source: http://arxiv.org/abs/gr-qc/0411063v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; G. N. Shikin

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We prove some theorems characterizing the global properties of static, spherically symmetric configurations of a self-gravitating real scalar field in general relativity (GR) in various dimensions, with an arbitrary potential $V$, not necessarily positive-definite. The results are extended to sigma models, scalar-tensor and curvature-nonlinear theories of gravity. We show that the list of all possible types of space-time causal structure in the models under study is the same as for a constant...

Source: http://arxiv.org/abs/gr-qc/0109027v1

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Sep 24, 2013
09/13

by
K. A. Bronnikov; V. N. Melnikov

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We discuss possible observational manifestations of static, spherically symmetric solutions of a class of multidimensional theories of gravity, which includes the low energy limits of supergravities and superstring theories as special cases. We discuss the choice of a physical conformal frame to be used for the description of observations. General expressions are given for (i) the Eddington parameters $\beta$ and $\gamma$, characterizing the post-Newtonian gravitational field of a central body,...

Source: http://arxiv.org/abs/gr-qc/0103079v1

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Sep 19, 2013
09/13

by
K. A. Bronnikov; M. S. Chernakova

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We consider static, spherically symmetric, electrically or/and magnetically charged configurations of a minimally coupled scalar field with an arbitrary potential $V(\phi)$ in general relativity. Using the inverse problem method, we obtain a four-parameter family of asymptotically dS, flat and AdS solutions, including those with naked singularities and both extreme and non-extreme black-hole (BH) solutions. The parameters are identified as the asymptotic cosmological constant, an arbitrary...

Source: http://arxiv.org/abs/gr-qc/0703107v1

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Sep 19, 2013
09/13

by
K. A. Bronnikov; E. V. Donskoy

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A black universe is a nonsingular black hole where, beyond the horizon, there is an expanding, asymptotically isotropic universe. Such spherically symmetric configurations have been recently found as solutions to the Einstein equations with phantom scalar fields (with negative kinetic energy) as sources of gravity. They have a Schwarzschild-like causal structure but a de Sitter infinity instead of a singularity. It is attempted to obtain similar configurations without phantoms, in the framework...

Source: http://arxiv.org/abs/0910.4930v1

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Sep 18, 2013
09/13

by
K. A. Bronnikov; S. V. Grinyok

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We study the stability of static, spherically symmetric, traversable wormholes with or without an electric charge, existing due to conformal continuations in a class of scalar-tensor theories with zero scalar field potential (so that Penney's or Fisher's well-known solutions hold in the Einstein conformal frame). Specific examples of such wormholes are those with nonminimally (e.g., conformally) coupled scalar fields. All boundary conditions for scalar and metric perturbations are taken into...

Source: http://arxiv.org/abs/gr-qc/0509062v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; O. B. Zaslavskii

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We consider the properties of stress-energy tensors compatible with a Null Big Bang, i.e., cosmological evolution starting from a Killing horizon rather than a singularity. For Kantowski-Sachs cosmologies, it is shown that if matter satisfies the Null Energy Condition (NEC), then (i) regular cosmological evolution can only start from a Killing horizon, (ii) matter is absent at the horizon, and (iii) matter can only appear in the cosmological region due to interaction with vacuum. The latter is...

Source: http://arxiv.org/abs/0710.5618v3

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Sep 18, 2013
09/13

by
K. A. Bronnikov; G. N. Shikin

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Static, cylindrically symmetric solutions to nonlinear scalar-Einstein equations are considered. Regularity conditions on the symmetry axis and flat or string asymptotic conditions are formulated in order to select soliton-like solutions. Some non-existence theorems are proved, in particular, theorems asserting (i) the absence of black-hole and wormhole-like cylindrically symmetric solutions for any static scalar fields minimally coupled to gravity and (ii) the absence of solutions with a...

Source: http://arxiv.org/abs/gr-qc/0101086v1

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Sep 23, 2013
09/13

by
K. A. Bronnikov; J. C. Fabris; A. Zhidenko

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We study the stability of static, spherically symmetric solutions to the Einstein equations with a scalar field as the source. We describe a general methodology of studying small radial perturbations of scalar-vacuum configurations with arbitrary potentials V(\phi), and in particular space-times with throats (including wormholes), which are possible if the scalar is phantom. At such a throat, the effective potential for perturbations V_eff has a positive pole (a potential wall) that prevents a...

Source: http://arxiv.org/abs/1109.6576v2

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Sep 18, 2013
09/13

by
K. A. Bronnikov; E. N. Chudaeva; G. N. Shikin

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We study the evolution of Bianchi-I space-times filled with a global unidirectional electromagnetic field $F_{mn}$ interacting with a massless scalar dilatonic field according to the law \Psi(\phi) F^{mn} F_{mn} where \Psi(\phi) > 0 is an arbitrary function. A qualitative study, among other results, shows that (i) the volume factor always evolves monotonically, (ii) there exist models becoming isotropic at late times and (iii) the expansion generically starts from a singularity but there can...

Source: http://arxiv.org/abs/gr-qc/0401125v1

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Sep 20, 2013
09/13

by
K. A. Bronnikov; R. A. Konoplya; A. Zhidenko

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We test the stability of various wormholes and black holes supported by a scalar field with a negative kinetic term. The general axial perturbations and the monopole type of polar perturbations are considered in the linear approximation. Two classes of objects are considered: (i) wormholes with flat asymptotic behavior at one end and AdS on the other (M-AdS wormholes) and (ii) regular black holes with asymptotically de Sitter expansion far beyond the horizon (the so-called black universes). A...

Source: http://arxiv.org/abs/1205.2224v3

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Sep 17, 2013
09/13

by
K. A. Bronnikov; S. G. Rubin; I. V. Svadkovsky

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Starting from pure multidimensional gravity with curvature-nonlinear terms but no matter fields in the initial action, we obtain a cosmological model with two effective scalar fields related to the size of two extra factor spaces. The model includes both an early inflationary stage and that of modern accelerated expansion and satisfies the observational data. There are no small parameters; the effective inflaton mass depends on the initial conditions which explain its small value as compared to...

Source: http://arxiv.org/abs/0912.4862v1

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Sep 18, 2013
09/13

by
K. A. Bronnikov; S. B. Fadeev; A. V. Michtchenko

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Global properties of static, spherically symmetric configurations of scalar fields of sigma-model type with arbitrary potentials are studied in $D$ dimensions, including space-times containing multiple internal factor spaces. The latter are assumed to be Einstein spaces, not necessarily Ricci-flat, and the potential $V$ includes contributions from their curvatures. The following results generalize those known in four dimensions: (A) a no-hair theorem: in case $V\geq 0$, an asymptotically flat...

Source: http://arxiv.org/abs/gr-qc/0212065v1

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Sep 21, 2013
09/13

by
S. V. Bolokhov; K. A. Bronnikov; S. G. Rubin

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The Higgs boson of the Standard model is described by a set of off-diagonal components of the multidimensional metric tensor, as well as the gauge fields. In the low-energy limit, the basic properties of the Higgs boson are reproduced, including the shape of the potential and interactions with the gauge fields of the electroweak part of the Standard model.

Source: http://arxiv.org/abs/1011.2828v2

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Sep 18, 2013
09/13

by
K. A. Bronnikov; H. Dehnen; V. N. Melnikov

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We give a comparative description of different types of regular static, spherically symmetric black holes (BHs) and discuss in more detail their particular type, which we suggest to call black universes. The latter have a Schwarzschild-like causal structure, but inside the horizon there is an expanding Kantowski-Sachs universe and a de Sitter infinity instead of a singularity. Thus a hypothetic BH explorer gets a chance to survive. Solutions of this kind are naturally obtained if one considers...

Source: http://arxiv.org/abs/gr-qc/0611022v2

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Sep 22, 2013
09/13

by
K. A. Bronnikov; G. N. Shikin; E. N. Sibileva

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We consider static, cylindrically symmetric configurations in general relativity coupled to nonlinear electrodynamics (NED) with an arbitrary gauge-invariant Lagrangian of the form $L_{em}= \Phi(F)$, $F =F_{mn}F^{mn}$. We study electric and magnetic fields with three possible orientations: radial (R), longitudinal (L) and azimuthal (A), and try to find solitonic stringlike solutions, having a regular axis and a flat metric at large $r$, with a possible angular defect. Assuming the function...

Source: http://arxiv.org/abs/gr-qc/0308002v1

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Sep 21, 2013
09/13

by
K. A. Bronnikov; S. V. Chervon; S. V. Sushkov

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We consider static, spherically symmetric solutions of general relativity with a nonlinear sigma model (NSM) as a source, i.e., a set of scalar fields $\Phi = (\Phi^1,...,\Phi^n)$ (so-called chiral fields) parametrizing a target space with a metric $h_{ab}(\Phi)$. For NSM with zero potential $V(\Phi)$, it is shown that the space-time geometry is the same as with a single scalar field but depends on $h_{ab}$. If the matrix $h_{ab}$ is positive-definite, we obtain the Fisher metric, originally...

Source: http://arxiv.org/abs/0905.3804v1

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27

Sep 20, 2013
09/13

by
K. A. Bronnikov; S. A. Kononogov; V. N. Melnikov

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We discuss possible variations of the effective gravitational constant with length scale, predicted by most of alternative theories of gravity and unified models of physical interactions. After a brief general exposition, we review in more detail the predicted corrections to Newton's law of gravity in diverse brane world models. We consider various configurations in 5 dimensions (flat, de Sitter and AdS branes in Einstein and Einstein-Gauss-Bonnet theories, with and without induced gravity and...

Source: http://arxiv.org/abs/gr-qc/0601114v2

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22

Sep 19, 2013
09/13

by
K. A. Bronnikov; H. Dehnen; V. N. Melnikov

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We use the general solution to the trace of the 4-dimensional Einstein equations for static, spherically symmetric configurations as a basis for finding a general class of black hole (BH) metrics, containing one arbitrary function $g_{tt} = A(r)$ which vanishes at some $r = r_h > 0$, the horizon radius. Under certain reasonable restrictions, BH metrics are found with or without matter and, depending on the boundary conditions, can be asymptotically flat or have any other prescribed large $r$...

Source: http://arxiv.org/abs/gr-qc/0304068v1

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18

Sep 19, 2013
09/13

by
K. A. Bronnikov; R. V. Konoplich; S. G. Rubin

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We show that a number of problems of modern cosmology may be solved in the framework of multidimensional gravity with high-order curvature invariants, without invoking other fields. We use a method employing a slow-change approximation, able to work with rather a general form of the gravitational action, and consider Kaluza-Klein type space-times with one or several extra factor spaces. A vast choice of effective theories suggested by the present framework may be stressed: even if the initial...

Source: http://arxiv.org/abs/gr-qc/0610003v2